/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.res;

import java.text.MessageFormat;
import java.util.Hashtable;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

/**
 * An internationalization / localization helper class which reduces the bother
 * of handling ResourceBundles and takes care of the common cases of message
 * formating which otherwise require the creation of Object arrays and such.
 * 
 * <p>
 * The StringManager operates on a package basis. One StringManager per package
 * can be created and accessed via the getManager method call.
 * 
 * <p>
 * The StringManager will look for a ResourceBundle named by the package name
 * given plus the suffix of "LocalStrings". In practice, this means that the
 * localized information will be contained in a LocalStrings.properties file
 * located in the package directory of the classpath.
 * 
 * <p>
 * Please see the documentation for java.util.ResourceBundle for more
 * information.
 * 
 * @version $Revision: 467222 $ $Date: 2006-10-24 11:17:11 +0800 (星期二, 24 十月
 *          2006) $
 * 
 * @author James Duncan Davidson [duncan@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Mel Martinez [mmartinez@g1440.com]
 * @see java.util.ResourceBundle
 */

public class StringManager {

	/**
	 * The ResourceBundle for this StringManager.
	 */

	private ResourceBundle bundle;
	private Locale locale;

	/**
	 * Creates a new StringManager for a given package. This is a private method
	 * and all access to it is arbitrated by the static getManager method call
	 * so that only one StringManager per package will be created.
	 * 
	 * @param packageName
	 *            Name of package to create StringManager for.
	 */

	private StringManager(String packageName) {
		this(packageName, Locale.getDefault());
	}

	private StringManager(String packageName, Locale loc) {
		String bundleName = packageName + ".LocalStrings";
		bundle = ResourceBundle.getBundle(bundleName, loc);
		// Get the actual locale, which may be different from the requested one
		locale = bundle.getLocale();
	}

	private StringManager(ResourceBundle bundle) {
		this.bundle = bundle;
		locale = bundle.getLocale();
	}

	/**
	 * Get a string from the underlying resource bundle or return null if the
	 * String is not found.
	 * 
	 * @param key
	 *            to desired resource String
	 * @return resource String matching <i>key</i> from underlying bundle or
	 *         null if not found.
	 * @throws IllegalArgumentException
	 *             if <i>key</i> is null.
	 */

	public String getString(String key) {
		if (key == null) {
			String msg = "key may not have a null value";

			throw new IllegalArgumentException(msg);
		}

		String str = null;

		try {
			str = bundle.getString(key);
		} catch (MissingResourceException mre) {
			// bad: shouldn't mask an exception the following way:
			// str = "[cannot find message associated with key '" + key + "' due
			// to " + mre + "]";
			// because it hides the fact that the String was missing
			// from the calling code.
			// good: could just throw the exception (or wrap it in another)
			// but that would probably cause much havoc on existing
			// code.
			// better: consistent with container pattern to
			// simply return null. Calling code can then do
			// a null check.
			str = null;
		}

		return str;
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the
	 * given set of arguments.
	 * 
	 * @param key
	 * @param args
	 */

	public String getString(String key, Object[] args) {
		String iString = null;
		String value = getString(key);

		// this check for the runtime exception is some pre 1.1.6
		// VM's don't do an automatic toString() on the passed in
		// objects and barf out

		try {
			// ensure the arguments are not null so pre 1.2 VM's don't barf
			if (args == null) {
				args = new Object[1];
			}

			Object[] nonNullArgs = args;
			for (int i = 0; i < args.length; i++) {
				if (args[i] == null) {
					if (nonNullArgs == args) {
						nonNullArgs = (Object[]) args.clone();
					}
					nonNullArgs[i] = "null";
				}
			}
			if (value == null)
				value = key;
			MessageFormat mf = new MessageFormat(value);
			mf.setLocale(locale);
			iString = mf.format(nonNullArgs, new StringBuffer(), null)
					.toString();
		} catch (IllegalArgumentException iae) {
			StringBuffer buf = new StringBuffer();
			buf.append(value);
			for (int i = 0; i < args.length; i++) {
				buf.append(" arg[" + i + "]=" + args[i]);
			}
			iString = buf.toString();
		}
		return iString;
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the
	 * given object argument. This argument can of course be a String object.
	 * 
	 * @param key
	 * @param arg
	 */

	public String getString(String key, Object arg) {
		Object[] args = new Object[] { arg };
		return getString(key, args);
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the
	 * given object arguments. These arguments can of course be String objects.
	 * 
	 * @param key
	 * @param arg1
	 * @param arg2
	 */

	public String getString(String key, Object arg1, Object arg2) {
		Object[] args = new Object[] { arg1, arg2 };
		return getString(key, args);
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the
	 * given object arguments. These arguments can of course be String objects.
	 * 
	 * @param key
	 * @param arg1
	 * @param arg2
	 * @param arg3
	 */

	public String getString(String key, Object arg1, Object arg2, Object arg3) {
		Object[] args = new Object[] { arg1, arg2, arg3 };
		return getString(key, args);
	}

	/**
	 * Get a string from the underlying resource bundle and format it with the
	 * given object arguments. These arguments can of course be String objects.
	 * 
	 * @param key
	 * @param arg1
	 * @param arg2
	 * @param arg3
	 * @param arg4
	 */

	public String getString(String key, Object arg1, Object arg2, Object arg3,
			Object arg4) {
		Object[] args = new Object[] { arg1, arg2, arg3, arg4 };
		return getString(key, args);
	}

	// --------------------------------------------------------------
	// STATIC SUPPORT METHODS
	// --------------------------------------------------------------

	private static Hashtable managers = new Hashtable();

	/**
	 * Get the StringManager for a particular package. If a manager for a
	 * package already exists, it will be reused, else a new StringManager will
	 * be created and returned.
	 * 
	 * @param packageName
	 *            The package name
	 */
	public synchronized static StringManager getManager(String packageName) {
		StringManager mgr = (StringManager) managers.get(packageName);
		if (mgr == null) {
			mgr = new StringManager(packageName);
			managers.put(packageName, mgr);
		}
		return mgr;
	}

	/**
	 * Get the StringManager for a particular package. If a manager for a
	 * package already exists, it will be reused, else a new StringManager will
	 * be created and returned.
	 * 
	 * @param bundle
	 *            The resource bundle
	 */
	public synchronized static StringManager getManager(ResourceBundle bundle) {
		return new StringManager(bundle);
	}

	/**
	 * Get the StringManager for a particular package and Locale. If a manager
	 * for a package already exists, it will be reused, else a new StringManager
	 * will be created for that Locale and returned.
	 * 
	 * @param packageName
	 *            The package name
	 * @param loc
	 *            The locale
	 */

	public synchronized static StringManager getManager(String packageName,
			Locale loc) {
		StringManager mgr = (StringManager) managers.get(packageName + "_"
				+ loc.toString());
		if (mgr == null) {
			mgr = new StringManager(packageName, loc);
			managers.put(packageName + "_" + loc.toString(), mgr);
		}
		return mgr;
	}

}
